1. Field of the Invention
The subject invention is related to wind turbines and is specifically directed to shroud and ring gear drive configurations for reducing gear tooth loading and thereby increasing gearbox torque transmission capability by reducing gear tooth tangential force.
2. Description of the Prior Art
Wind turbines, like other energy conversion devices, require fuel. It is the quantity of fuel available to the device and the overall conversion efficiency that ultimately determine the net power output. In the case of a wind turbine, air is the fuel. The quantity of air available to the turbine is determined by the diameter of the rotor and the elevation at which the rotor is positioned. A large diameter turbine rotor located atop an extremely tall tower has more air available to it due to increases in mean wind speed and swept rotor area. A consequence of this factor is that rotor, drive train and tower loads increase.
Upwind rotor designs currently in use are not operated at optimum structural efficiency. Rotor power ratings are largely influenced by blade tip to tower clearance limitations, materials of construction, and quality of workmanship. Any given rotor design can be maximized to provide optimum power output if adequate tower clearance is provided.
It is a goal of the wind turbine industry to be able to produce power at competitive rates, with the current target cost of energy (“COE”) being in the range of $0.025/kWh to $0.029/kWh. Current technology generally has a COE of over $0.035/kWh. Therefore, in order to achieve the target COE, a novel configuration is required.
From the viewpoint of addressing only wind turbine design to achieve a low COE, two parameters can be optimized to produce the lowest possible COE. These are the cost of turbine hardware and the turbine performance. Hardware costs directly affect the initial capital cost and turbine performance is directly related to net annual energy production. In order to reach the goal of $0.025/kWh wind power electrical energy production, innovative configuration changes in traditionally designed wind turbines is required.